Technical Field
The present disclosure relates generally to precision metrology, and more particularly to induced current linear and rotary absolute position encoders.
Description of the Related Art
Induced current position encoders typically have a readhead that is movable relative to a scale member, and includes one or more transducers comprising an excitation winding and receiver winding(s). The receiver winding(s) may have a wavelength which is different for different transducers. Each transducer will have a scale or track on the scale member which includes a plurality of flux modulators. The flux modulators may each have a length along the measuring axis that is equal to one-half of the wavelength of the corresponding receiver winding(s).
U.S. Pat. No. 6,329,813, which is commonly assigned and hereby incorporated herein by reference in its entirety, discloses an absolute position encoder transducer with improved winding configurations which increase the proportion of the useful output signal component relative to extraneous (“offset”) components of the output signal.
While the '813 patent provides improved winding configurations, the length that the absolute scale can be extended to for a given scale width and accuracy or resolution remains limited (e.g., due in part to limitations for the fabrication accuracy and signal interpolation of such readheads). A need exists for a compact position encoder capable of longer absolute ranges with high accuracy.